Of late, the hot-box process of making cores directly in core boxes have found extensive application in foundry practice the world over.
Foundry plants of the machine-building industry are now engaged in the production of core-making machines which are based on the above-mentioned operating principle.
This type of core-making machine incorporates a core-blowing machine, devices for separation of core boxes and for delivery of finished cores, appliances for heating the core boxes, and transport means for conveying these boxes from one station to another. There are known shuttle- and rotary-type core-making machines (see, for example, a book by G. V. Prosianik, G. I. Bobriakov, V. A. Sokolova, P. G. Danilevskaya, M. K. Sokov, V. V. Lubimov, entitled "Production of Cores in Hot Boxes," Mashinostroenie Publishers, Moscow, 1970, pp. 147-148, 152-154).
The core delivery device, incorporated in such machines, normally comprises a delivery table and a drive for its rotation or movement. After the core box has been disassembled, the cores are transferred onto the delivery table. In the machines designed for the production of small-size cores, the delivery tables are made rotatable so as to deliver cores from the core box directly, or over an inclined surface, into a charging trough from where they are removed by an operator.
The delivery tables incorporated in the machines designed for the production of large-size cores are usually made for horizontal movement, during which the cores are delivered to an operator. The removal of cores from the tables and their further delivery onto transport means are carried out manually.
Since in the hot-box process the hardening of sand proceeds uniformly under the effect of heat and a catalyst due to a rapid polymerization of a bender, there is no necessity in weighing the cores.
There is known another core-making process which consists in that a fluidized sand is packed under pressure in a hot box (cf. U.S. Pat. No. 3,802,484, Cl. 164-169).
The cores made in accordance with the above method have an interior channel or porosity which ensure effective ventilation of the cores at a time when metal is poured into a mould and when an ingot undergoes cooling. This being the case, the cores are preferably weighed with the purpose of determining the size of the interior channel or the extent of their porosity before they are removed from the machine.
There is also known a multi-station machine for producing cores from fluidized sands in hot boxes. The machine is made in two stages and has floating core boxes. The removal of cores directly from the delivery table is impossible. Mounted on the lower stage of the machine are transport means and delivery tables. Arranged on the upper stage of the machine in the direction of the technological process are a device for preparation of sand, a packing mechanism, a pusher, a heating chamber, a device for separating core boxes, and a device for the delivery of finished cores.
The core delivery device of this machine comprises a trolley mounted for reciprocation on a support frame and carrying an arrangement for receiving cores and delivering them onto the bearing plate bars mounted on the support frame (see, for example, patent application No. 2,057,318 laid out with the UK Patent Office on Apr. 1, 1981).
In the core delivery device referred to above, the mechanism for receiving cores and delivering them onto the bearing plate bars is made in the form of a Y-shaped plate mounted on the trolley and having its projections directed towards a core box and carrying stops fitted on the butt ends thereof.
The trolley incorporated in the above device has dogs for pushing the cores. The bearing plate bars have horizontal and inclined sections, the latter being directed towards the core box. The horizontal section of the plate is arranged at a level somewhat higher than the plane of the Y-shaped plate in which lies the core, the lower end of the inclined section of each bearing plate bar being disposed below this plane.
The above-described device for the delivery of cores operates as follows.
As the trolley moves toward the disassembled core box, the Y-shaped plate of the core receiving and delivering arrangement is brought under the core positioned on the core-box pushers; the pushers are lowered to place the core on the Y-shaped plate. Further, the trolley is caused to move in the opposite direction, the core is withdrawn from the core box and, running against the inclined section of the bearing plate bars, is pushed thereon by means of the stops provided in the core receiving and delivering arrangement. With each travelling cycle of the trolley, the core is pushed further along over the inclined and then over the horizontal section of the bearing plate bars to a weighing means and then to a core discharging station.
While moving over the bearing plate bars from the core box to the core discharging station, the core wears out under the action of its weight. As this happens, the film of a binding agent is removed, the surface smoothness is deteriorated, and collapsibility of the core is due to occur at the places of its wear. This, in turn, may lead to the production of defective ingots.
The fact that the cores are pushed over the bearing plate bars renders impossible the transportation of complex-shaped cores having protruded parts on their lower surfaces.
Moreover, the above construction of the core delivery device complicates their delivery onto a weighing means, as well as onto transport means for conveying the cores to successive stations.